This invention relates to insecticides. More particularly, in a preferred aspect it relates to an improved method for enhancing effectiveness of dithiophosphate insecticides in absorption by certain insects to effect a kill.
Dithiophosphate insecticides of the type with which the present invention is concerned may be represented by the formula: ##STR1## in which R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each an aliphatic or aromatic hydrocarbon radical. Such esters are well known and may be conveniently prepared, for instance, by reacting an O,O-dialkyl dithiophosphate with a dialkyl maleate as described and claimed in U.S. Pat. No. 2,578,652. A typical and well known ester of this class is O,O-dimethyl-S-(1,2-dicarbethoxyethyl)-dithiophosphate which is commercially available as "Malathion.RTM.." It is with this latter compound that much of the test experience with the present invention is particularly concerned. The following description does apply to dithiophosphate ester insecticides in general, and as explained later, to a broader class of insecticides as well. Thus, it is to be understood that the present process is equally as applicable to other insecticides besides dithiophosphate esters.
As heretofore mentioned, such dithiophosphate ester insecticides and their preparation are known and have been known and effective for many years. However, their effectiveness against some insects of which red fire ants are but one example, has been somewhat limited at lower concentrations.
Other classic insecticide classes besides the organo phosphates and dithiophosphate esters in particular are also in need of enhanced effectiveness for certain insects. Examples of such other insecticide classes include carbamates, chlorinated hydrocarbons, synthetic pyrethroids, insect growth regulators, botanicals such as nicotine plant derivatives and naturally occurring insecticides such as boron and arsenic compounds. These are all within the scope of the present invention.
Moreover, in order to minimize pollution risks, there are always continuing efforts towards increasing the effectiveness of known insecticides from the standpoint of the ability to achieve the same level of effectiveness, but with less insecticide.
Accordingly, it is a primary objective of the present invention to provide a composition which enhances the effectiveness of certain classic types of insecticides, particularly the preferred dithiophosphate pesticides like Malathion.RTM..
Another objective of the present invention is to achieve enhanced effectiveness of insecticides by enhancing the ability of the insecticide to be absorbed by cell membranes of the exterior cell layers of the insect, thereby substantially increasing the effectiveness and thus allowing reduction of the treatment or dosage level required.
Another objective of the present invention is to provide an insecticide effectiveness enhancing composition which uses as an additive a polluting free additive that is environmentally unobjectionable.
The method and means of accomplishing each of the above objectives will become apparent from the detailed description of the invention which follows.